Thread-cutting mechanism.



E. B. ALLEN.

THREAD CUTTINGMECHANISM.

APPLICAI ION FILED DEC. l 6. I912. 1 15mm Patentedsept. 14, 1915.

.. J 1 n QWXMN w m. Q v m -gk w 8 as PATENT option EDWARD B. ALLEN, OF BRIDGEPOBT, CONNECTICUT, ,ASSIGNOR TO THE SINGER MANUFACTURING COMPANY, A CORPORATION OF, NEW JERSEY.

THREAD-CUTTING- MECHANISM.

Specification of Letters Patent.

Patented Sept. 14, T215.

Application filed December 16, 1912. Serial No. 736,953.

To all whom it may concern:

Be it known that I, EDWARD B. ALLEN, a citizen of the United States, residing at Bridgeport, in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Thread- Gutting Mechanisms, of which the following is a specification, reference being had therein to the accompanying drawings.

This invention has for its object to provide a simple and effective thread-cutting connected with one arm of a rocking pln journaled in the bed-plate andcarrying a second arm disposed in. operative relation with a cam projection upon the feed-cam wheel which imparts operative movements to the traveling work-clamp. The upper member of the work-clamp is controlled in its movements toward and from the work by a rocking cam element formed with a tappet arm which, when the clamp is closed, extends within the path of'movement of a tripping pin mounted upon the slide-bar of the thread-cutting mechanism. As the thread-cutting knife is actuated tocut the thread by the advance of the slide-bar, the tripping pin encounters the tappet arm of the clamp-controlling cam element which is shifted for opening the clamp to release the work at the completion of a stitching operation.

The present improvement is shown in the accompanying drawings applied to a Singer eyelet-end buttonhole machine constructed substantially in accordance with that disclosed in my pending application Serial No.

7 693,778, filed-April 29, 1912.

ent improvement omitted. Fig. 2 is a side elevation of the work-clamp with parts of 'its opening and closing means and the thread-cutting mechanism; and Fig. 3 is a plan of the thread-cutting mechanism. Fig. 4 1s a side elevation of the work-clamp similar to Fig. 2 but taken-from the opposite side to show other parts of the clamp than those represented in Figs. 1 and 2.

As represented in the drawings, the sewlng machine base comprises the parallel sides 1 and superposed bed-plate 2 having in its forward portion the guideways 3 to receive the longitudinally moving slide-plate of the work-clamp upon which is superposed the usual cross slide-plate carrying reciprocally and edgewise movable lower work-clamping members 4 only one of which appears in the drawings. Upon each of the members 4 is secured a bracket 5 within a recess in which is pivotally mounted by means of the cross pin 6 the rocking block 7 upon which is secured by the screw 8 the rearward end portion of the clamp-arm 9 whose downwardly offset forward portion 10 constitutes the upper clamping member.

J ournaled in suitable bearing bosses 11 of the bracket 5 is the transverse pin 12 carrying the collar 13 (shown in dotted lines in Fig. 1) provided with the cam projection 14 and from which extends the tappet arm 15. The turning of the collar 13 in one direction causes the engagement of thecam element 14 with the clamp-arm 9 to depress the upper clamp-member 10 in opposition to its lifting spring 16, and the turning of the collar 13 in the opposite direction relieves the pressure of the cam element 14 upon the clamp-arm and permits the latter to rise under the action of the spring 16 as represented in Fig. 2.

The pin 12 has fixed upon one end the finger-lever 17 and upon the opposite end the cam arm 18 formed on its rearward portion with the upwardly extending camshaped projection 19. Mounted upon a traveling fulcrum-pin 20 is a clamp-closing rock-lever composed of the forwardly extending arm 21 with downwardly curved extremity 22 and the rearwardly extending arm 23 having the fork 24 in its extremity. As'shown-and described in my said appli- .cation, the rock-lever 21 23 is in practice so mounted and actuated that it is caused to be advanced and tilted during a buttonhole cutting operation of the slit-cutting mechanism to engage the projection 19 of the cam- 110 arm 18 to rock the pin 12 and thereby turn the cam element 14 for depressing the upper clamp-member 10 upon the work, after which the rock-lever 21 23 retires and the clamp remains closed for a stitching operation.

As represented in the drawings, and as shown more fully in my- United States Patents No. 1,024,490, of April 30, 1912, and No. 1,048,786, of December 31, 1912, the stitch-forming mechanism comprises a reciprocatingand laterally jogging needle 25 working through an aperture 26 in the needle-throat 27 carried by a rigid arm 28 connected with the rotary looper-support 29- disposed beneath the bed-plate upon which is sustained the rocking looper-carrier 3O sustaining the threaded looper 31 and the non-threaded looper 32 operated in practice in conjunction with suitable loop-Spreaders.

Secured by means of screws 33 to the bottom of and extending beyond the for ward end of the bed-plate l is the bracketplate 34 carrying the fulcrum-stud'35 upon which is mounted the shank or stock 36 of the thread-cutting blade 37 whose sharp operative edge is shown slightly concaved at 37 As represented in Fig. 3, the fulcrumpin is so positioned that the eoncav'ed portion 37 of the blade 37 passes beneath the needle aperture, and hence across the needle-path, in moving from the full-line retracted position to dotted-line advance position, and. vice versa.

The shank 36 of the thread-cutting blade is formed with the elongated aperture 38 which is entered by the screw-stud 39 extending from the bottom of the forward portion of the slide-bar 40 fitted within a guideway formed therefor in the top of the bed-plate beneath the work-clamp, as represented in Fig. 1. In its rearward portion, the slide-bar is connected by means of the stud-pin 41 with one end of a link 42 whoseopposite end carries a screw-pin 43 embraced by a boss at the outer end of the lateral arm 44 provided with the hub 45 which is secured by means of the set-screw 46 upon the upper end of the vertical rocking pin 47 journaled in a suitable aperture in and extending through the bed-plate 1. Fixed upon the lower end of the pin 47 is the hub 48 of an arm 49 whose downturned extremity 50 lies in the path 01 movement of the cam projection 51 suitably secured within a notch in the periphery of the feed camwheel 52. The cam-wheel 52 has in its upper face the usual feed-cam groove 53 and side-shift groove 54 which in practice impart to the work-holder, through suitable connections therefor, the requisite longi tudinal feeding and sidewise shifting move-. ments of the work relatively to the stitchforming mechanism, the cam-wheel having step-by-step rotary movements imparted thereto during the stitching operation by mechanism including clutch-dogs 55 embracing a depending peripheral flange of the cam-wheel.

Secured upon the upper face of the slidebar 40 by screws 56 is the foot 57 of a post 58 having at its upper end the boss 59 in which is mounted the tripping pin 60 externally threaded through a part of its length to receive the thrust-nuts 61 embracing the boss 59 by means of which it is sustained in the desired position of adjustment. The post 58 carries a pin'62 formed with a transverse aperture in 'which is hooked one end of a spring 63 whose opposite end is similarly attached to an eye 64 secured in the'standard 1 of the sewing machine frame, as represented in dotted lines in Fig. 1. This springacts through the post 58 and slide-bar 40 to maintain the threadcutting blade normally in retracted position and the extremity 50 of the arm '49 continuously in contact with the periphery of the cam-wheel by means of which the operation of the cutter-blade is controlled.

As shown and described in my said application, each of the clamp-plates 4 sustains a bracket 5 which carries an upper, clamping member 9 controlled in its work-clamp action by means of cam element 14 fixed upon the rocking pin 12, and the rocking pins of the two clamping members are connected to rock simultaneously by means of radial arms 65 and 66fixed upon their adjacent ends respectively, the former being provided with a lateral stud 67 entering a fork 68 in the extremity of the arm 66. According to the present construction, the tappet arm 15 and cam-arm 18 carried by one of the rocking pins 12, and therefore operatively connected with its cam element 14, are not duplicated in connection with the other pin, as both of these pins are connected to move simultaneously, so that actuation of one causes a y corresponding actuation of the other.

In the use of the machine as thus described, the operation of the cloth-cutting mechanism serves to close the upper clam member upon the work in which relation it is retained under the action of the cam element 14 until the completion of the stitching operation. Just as the stitching operation ceases, the cam projection 51 engages the part 50 of the arm 49 and rocks the pin 47, whereby the arm 44 is moved to advance the slide-bar 40 which, through the described pin-and-slot connection actuates the thread-cutting blade 37. The tripping pin 60 is so ad usted upon the post 58 that as the slide-bar 40 nears its extreme operative position the forward end of the pin 60 encounters the tappet-arm 15, thus turning the clamp-arm controlling cam-elements 14 to release the upper clamp-bars which are thus lifted by their respective springs 16 to reme als work within the clamp.

By the means just described, a thread" cutting device is provided of very simple construction and thus not liable to get out of order and, one of 'which the actuating mechanism is entirely out of the operators way in the handling of the work or threading of the machine. It not only aflords a means of opening the work-clamp, but effects the release of the work at the earliest possible instant after the thread-cutting operation, the timing of the clamp-opening action being determined positively and accurately by'the very nature of the mechanism.

Having thus set forth the nature of the invention, what I claim herein is 1. In a buttonhole sewing machine, the combination with the bed-plate, a traveling work-clamp, a feed-Wheel disposed beneath the bed-plate for imparting operative movements to the work-clamp, and stitch-forming mechanism including a needle and looptaking means, of a thread-cutting blade movable. upon a fixed. fulcrum across the path of the needle, a slide-bar sustained by the bed-plate and having a pivotal connection with the thread-cutting blade, and means connected with and actuated by the feed-wheel for imparting to-and-fromovements to said slide-bar.

2. In a buttonhole sewing machine, the combination with the bed-plate, a traveling work-clamp, a feed-wheel disposed beneath the bed-plate for imparting operative movements to the work-clamp, and stitch-forming mechanism includinga needle and looptaking means, of a thread-cutting blade movable across the path of the needle, a' slide-bar sustained by the bed-plate and operatively connected with the thread-cutting blade, a rocking pin journaled in the bed-plate and having an arm connected with said slide-bar, and a second arm mounted upon said rocking pin beneath the bed-plate and disposed in operative relation with the feed-Wheel.

3. In a buttonhole sewing machine, the

around one of combination with the bed-plate formed in its upper side with a guideway, a traveling work-clamp, a feed-wheel disposed beneath the bed-plate for imparting operative movements to the work-clamp, and stitch-forming mechanism including a needle and looptaking means, of a thread-cutting blade movable across the path of the needle beneath .the work-clamp, a slide-bar mounted in said guideway of the bed-plate and operatively connected with the thread-cutting blade, a rocking pin journaled in the bedplate and having an arm secured thereon above the latter and a-second arm secured thereto beneath the bed-plate and in operative relation with the feed-wheel, and a link connection between the first-named arm of the rocking pin and said slide-bar.

4. In a buttonhole sewing machine, the combination. with stitch-forming mechanism including a needle and loop-taking means, a traveling work-clamp comprising separable clamping members, and a feed-Wheel for imparting operative movements to the Work-clamp, of 'a thread-cutting blade, means connected with feed-wheel for operating said blade, and means connected withthe blade operating means for opening the work-clamp.

5. In a buttonhole sewing machine, the combination with stitch-forming mechanism including aneedle and loop-taking means, a traveling work-clamp -comprising separable upper and lower members and a controlling rocking cam element therefor provided with a tappetarm, and a feed-wheel for imparting operative movements to the work-clamp, of a thread-cutting blade movable across the needle-path, a slide-bar operatively connected with said blade, means for imparting to-and-fro movements to said slide-bar, and a tripping pincarried by said slide-bar and adapted for engagement with the tappet arm of said cam element. 7

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

EDWARD B. ALLEN.

Witnesses:

E. L. Towns, STANLEY N. SMITH.

and actuated by the i 

